Nitric Acid Storage — Concentration-Dependent Tank Selection

Storing Nitric Acid? Read the Concentration First

Nitric acid is the one chemical where concentration decides everything. Dilute-to-mid nitric stores fine in a poly tank — but concentrated nitric (roughly 95%+) will destroy polyethylene. Most problems come from someone putting strong nitric in a poly tank that was fine for the dilute stuff. Check your strength before you spec the tank.

Can you store it in a poly tank? Up to a point.

• Up to ~30%: poly is fine, even when warm.
• 30–50%: poly works at room temperature; back off as it gets hot.
• ~70%: borderline — room-temp only, and many specs move to stainless here.
• 95%+ (fuming/concentrated): do not use polyethylene. Use 316L stainless, PTFE-lined, or glass-lined steel.

For the poly-compatible range, run a chemical-service tank (1.9 SG) and confirm gaskets/fittings against the manufacturer chart. Nitric is a strong oxidizer as well as an acid, so keep it away from organics and other chemicals.

The safety that actually matters

• Know your concentration before choosing the tank — it's the whole ballgame.
• Strong oxidizer: keep away from fuels, solvents, and organics.
• Secondary containment at 110%, eyewash/shower close by.

Common questions

Can I store concentrated nitric acid in a poly tank?

No. Above roughly 95% it destroys polyethylene — use 316L stainless, PTFE-lined, or glass-lined steel. Poly is only for the dilute-to-mid range.

What's the safe poly range?

Comfortably up to ~30%, workable to ~50% at room temp, borderline near 70%. Verify against the chart and your temperature.

Anything else to watch?

It's an oxidizer — segregate from organics and fuels, and contain it.